Kaposi Sarcoma Presenting as Tender Lesion on the Foot

Kaposi sarcoma (KS) is a hyperplasia or neoplasia caused by human herpesvirus 8 (HHV-8). This condition was first described in elderly Mediterranean and Ashkenazi Jews as an indolent cancer that was rarely fatal. HHV-8 is also associated with Castleman disease, a lymphoproliferative disorder. However, disease does not develop in most immunocompetent persons infected with HHV-8.

In the United States, KS is an uncommon disease of middle-aged and elderly American and European men of Mediterranean or Jewish descent. With the emergence of HIV, KS found a new incarnation in patients with AIDS. Histologically, KS manifests with spindle cells and an increased number of blood vessels. KS most commonly presents as well-defined red or purple patches that occur symmetrically on both feet and legs and can progress to nodules and tumors.

Cutaneous KS typically occurs in 6 stages: patch (A), plaque (B), nodular (C), exophytic, infiltrative, and lymphadenopathic. The classic form of KS, which affects elderly men, appears initially as discrete, symmetric red or purple patches that often involve both legs or just a few toes. Patches become elevated and evolve into soft or friable nodules and plaques. Nodules may be spongy to the touch. Immunocompetent persons whose lesions progress slowly require only observation. As opposed to KS in persons with AIDS, classic KS is more indolent and circumscribed and less likely to progress.

In patients with HIV infection, the wide range of presentations of KS includes infiltrative or exophytic patterns. Rare presentations include telangiectatic, ecchymotic, keloidal, cavernous, and lymphangioma-like KS. KS may also affect the internal organs, particularly the lungs and intestines, with resulting hemorrhage and death. Chronic lymphedema may precede KS.

Biopsy is the definitive diagnostic tool for cutaneous KS. A new antibody stain for HHV-8 makes diagnosis easier. Indolent or limited lesions can be frozen or treated with alitretinoin gel. For more severe localized nodular disease, options include surgical excision, radiotherapy, and intralesional low-dose vinblastine chemotherapy. A variety of chemotherapeutic agents are available for severe cases.